Embodiments of the present disclosure may relate to a system and method for evaluating physiological parameter data. In embodiments, a medical device may be capable of calculating an airway instability index from pulse oximetry measurements and generating a smoothed index representing airway instability.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Obstructive sleep apnea is a condition in which a patient's breathing is temporarily interrupted when sleeping. The condition is believed to be associated with increased fat deposits in the neck, which commonly occur as a patient ages. These increased fat deposits may lead to a narrowing of the airway. When muscle tone diminishes during sleep, the narrowed airway can collapse during inhalation, effectively stopping and/or severely limiting air movement. At this point, the choking patient typically attempts to inhale more deeply, which generally results in further collapsing the airway. With no air movement, the oxygen level in the patient's bloodstream falls, finally reaching a point where the patient is aroused out of sleep. Upon arousal, the muscle tone increases, the airway opens and air flow to the lungs is precipitously restored. The patient hyperventilates, which quickly restores the blood oxygen levels to normal levels. The period of arousal is brief, so the patient is often unaware that the event took place. The patient returns to sleeping and the cycle often repeats.
Over time, this repeating cycle of low oxygen levels in the bloodstream can damage the heart and lead to other serious medical complications. Obstructive sleep apnea is believed to be one of the most common disorders in the United States and an important cause of heart attack and stroke. However, unlike other common medical disorders, such as diabetes, no simple diagnostic test has been developed to determine if a patient has sleep apnea. Tests do exist that can be used to diagnose sleep apnea, but the tests typically involve an overnight sleep study, which can be costly and inconvenient. The need for a simple, low-cost diagnostic test has led medical personnel to try less expensive techniques, such as pulse oximetry, to diagnose the presence of obstructive sleep apnea.